Voice over Internet Protocol (IP), referred to as “VoIP,” is a collection of technologies for delivering voice communications and/or multi-media sessions over an IP network. Whereas a conventional telephone system sends data over a circuit-switched network referred to as the Public Switched Telephone Network (PSTN), a VoIP telephone system sends data in the form of IP packets over a packet-switched network.
Like other real-time applications, VoIP requires minimum service guarantees that typically surpass the “best-effort” structure of modern IP networks. Delays as small as approximately 100 milliseconds can be detected by humans. Such delays can impair the interactivity of a conversation conducted over a call. Various factors relating to the network itself such as packet loss and packet delay are known to affect the perceived quality of a VoIP call. In addition, other factors relating to the VoIP phone itself also play a role perceived quality of a VoIP call.